Crystallization and preliminary X-ray analysis of the catalytic core of the alkylhydroperoxide reductase component AhpF from Escherichia coli

Alkylhydroperoxide reductases (AhpR, E.C. 1.6.4x) are essential for the oxygen tolerance of aerobic organisms, converting otherwise toxic hydroperoxides of lipids or nucleic acids to their corresponding alcohols. The AhpF component (521 amino-acid residues, 56.2 kDa) belongs to the family of pyridine nucleotide-disulfide oxidoreductases and channels electrons from NAD(P)H via a series of disulfides towards the AhpC component, which finally reduces the hydroperoxide substrates. Crystals of the proteolytically truncated AhpF component (residues Asn208-Ala521) of the alkyl hydroperoxide reductase from Escherichia coli were grown under oxidizing conditions. The crystals belong to space group P3(2)21, with unit-cell parameters a = 60.4, c = 171.8 Angstrom. X-ray diffraction data were collected to 1.9 Angstrom resolution using synchrotron radiation. A molecular-replacement solution was found using the structure of thioredoxin reductase from Arabidopsis thaliana as a search model.